Clarifying the impact of cueing on pharyngeal swallow timing in healthy adults.

PURPOSE: Cued swallows are often used during videofluoroscopy (VFSS) to capture bolus entry into the pharynx while limiting radiation exposure. Two prior studies in healthy adults report that cueing alters swallow timing measures, with shorter swallow reaction time (SRT) seen in cued swallows. To better understand the impact of cueing on swallow timing, VFSS data from a set of healthy adults were examined.METHODS: Data were collected in healthy adults, with no history or symptoms of dysphagia. Participants underwent a VFSS (30 frames/second), in which blocks of three comfortable sips of 20% w/v thin liquid barium (E-Z-Paque) were swallowed in cued and non-cued conditions. In the cued condition, participants held the bolus in the mouth for ~3 seconds until a “swallow” command was provided by the clinician. Blinded duplicate rating was completed according to the ASPEKT Method, with discrepancy resolution by consensus. Wilcoxon signed rank tests were performed to identify differences in participant-mean values for SRT, time-to-laryngeal-vestibule-closure (TTLVC), the hyoid-burst-to-upper-esophageal-sphincter(UES)-opening interval, UES opening duration, and LVC duration. Odds ratios were calculated for the frequency of atypical values, beyond currently proposed clinical decision limits (CDL), by condition (α = .05).RESULTS: Data were available from 12 participants (5 male; mean age 61 years, range 26-85). Hyoid burst onset occurred prior to bolus entry into the pharynx in 17% and 42% of participants in the uncued and cued conditions, respectively (χ2 = non-significant). Mean (± standard deviation) values for SRT were 4±5 frames (uncued) and 7±16 frames (cued): Z = -.934, non-significant). There were no significant differences in any timing measures, or in the frequency of atypical values across conditions.CONCLUSION: In this set of healthy adults, swallow timing measures did not confirm previously reported significant differences between cued and non-cued swallows. Possible reasons for this discrepancy include differences in participant age, the number of swallows sampled, the specific cues provided to participants and analysis methods. The current data suggest that current reference values for timing measures from uncued thin liquid swallows can be used to determine whether atypical timing is seen during cued swallows